A cylinder head cover, also referred to as a valve cover, is known to be the topmost end of an (upright) four-stroke internal combustion engine.
It harbors the upper actuation elements of the valve train and prevents the lubricating oil from leaking into the environment, and the air from entering the engine.
If the valve train is equipped with an overhead camshaft and the latter is driven by a chain, the cylinder head cover also comprises the camshaft sprockets.
Modern vehicles have a camshaft adjustment, also referred to as a variable camshaft control or variable valve control. This means a method for changing the timing of the valve control of four-stroke engines in operation.
The adjustment of the valve opening times allows the efficiency of the engine to be enhanced, depending on the respective load behavior.
In camshaft adjustment, the inlet and outlet timing is changed by actuators as a function of the revolutions per minute and the throttle position, in order to achieve as efficient as possible a cylinder filling in all speed ranges. Actuators transform electrical signals into mechanical movement in camshaft adjustment, and thus actively intervene with the control system.
The actuator discussed here displaces a cam pack on the camshaft so that a second cam becomes engaged on the valve. Because of the required precision, only aluminum covers are currently being employed for receiving the actuators.
From KU Kunststoffe, vol. 91 (2001) 6, cylinder head covers of polyamide 66 filled with glass fibers and minerals are known that meet all requirements relating to the mechanical load on cylinder head covers even at elevated temperatures, and are supposed to have a high creep strength.
From DE 198 04 607 C2, an assembly for electrically connecting at least one sensor is known, which is contacted through electric connecting lines and is provided on an engine component of an internal combustion engine that is at least partially made of plastic material, characterized in that the electric connecting lines (20) are designed in the form of metallic rails (21) and incorporated in the plastic material of the engine component (3), wherein a first end (24) of the rails (21) forms part of a connector holder (26), and a second end (25) of the rails (21) protruding from the plastic material of the engine component (3) provides corresponding connector contact points (18) for the sensor (1), which is electrically contactable with the rails (21) and thus with the connector holder (26) through a contact plate (14) with contact elements (22) provided between sensor connecting points (8) of the sensor (1) and the connector contact points (18) of the rails (21).
However, the engine components described therein do not comprise a cylinder head cover of a motor vehicle, and in particular, not a cylinder head cover made of plastic material and provided with an integrated camshaft timing mechanism. The metallic rails described therein do not serve to reinforce the engine component surrounding them.
The weight saving potential of plastic cylinder head covers as compared to known aluminum cylinder head covers is about 30 to 50%, a further cost benefit being achievable by consistent integration of functions into the component.
From ATZ—Automobiltechnische Zeitschrift, March 2007, vol. 109, pp. 220 to 224, hybrid covers made of plastic material are known. A cylinder head cover is described in which a rigid, but lightweight metal frame takes over the reinforcing function of the gasket. It is described that the bonding of the two materials can be effected only by an elastomer, in order to both ensure optimum acoustic decoupling and compensate for the different thermal expansions of the components. However, the metal stiffening frame has no contact with the cover body.
DE 198 04 607 C2 describes an assembly for electrically connecting at least one sensor. Said assembly for electrically connecting at least one sensor, which is contacted through electric connecting lines and is provided on an engine component of an internal combustion engine and is at least partially made of plastic material, is characterized in that said electric connecting lines are designed in the form of metallic rails and incorporated in the plastic material of the engine component, wherein a first end of the rails forms part of a connector holder, and a second end of the rails protruding from the plastic material of the engine component provides corresponding connector contact points for the sensor, which is electrically contactable with the rails and thus with the connector holder through a contact plate with contact elements provided between sensor connecting points of the sensor and the connector contact points of the rails. However, this is not a cylinder head cover.
DE 10 2004 026 658 A1 relates to a hybrid housing, especially an engine or gearbox housing. The application has the purpose to provide a housing, especially an engine or gearbox housing, that meets the required stability and precision demands, but has a reduced weight. For this purpose, the application provides a hybrid housing, especially an engine or gearbox housing, with a housing component of metal, on which at least a bearing seat is formed, wherein the housing component is coated with plastic on an interior side and/or exterior side, and the bearing seat is formed in a plastic-free region of the housing component. This publication does not include a cylinder head cover, either, especially not a metal bearing, and no fixture for an actuator. In addition, the housing is not oil-tight.
Hybrid technology is known to combine the properties of two materials, which combination achieves a higher performance than that of the individual materials.